Nucleation and Condensation in Polymer Systems

Abstract

Synthetic high-polymeric materials, particularly crystallizable ones, have the following two attributes which sharply distinguish them from most other substances: (1) essentially all of them were unknown as recently as thirty years ago, and (2) their molecules have an essentially thread-like shape. Liquids of metals or low-molecular-weight molecules can, to a good approximation, be regarded as aggregates of spheres, or at worst, ellipsoids of small axial ratio. On the other hand, the length of a typical, synthetic, high-polymer molecule is several thousand times its width. Thus, it is not surprising that synthetic high polymers exhibit properties that are very different from those of low-molecular-weight substances, e.g., rubbery behavior. The molecules of synthetic high polymers, being held together by covalent bonds, usually remain inviolate throughout the manipulations to which they are subjected. This is in contradistinction to the melting behavior of inorganic glasses where, because of structure, there must be interchange of bonds between neighboring atoms [¹].